There are a number of instances in building construction where a conduit, such as a round pipe, is routed to atmosphere at an open distal end. The roof of virtually any commercial or residential building will typically have one or more penetrations through which such pipes project. Some of these pipes are used for venting, such as for plumbing drains, furnace exhausts, and the like.
Usually, just leaving upwardly projecting pipe ends exposed to environmental elements is unacceptable. Left unshielded, rain, snow, dirt and debris will enter the open end and travel into the equipment at the other end of the pipe. In an exhaust line for a high efficiency furnace, for example, this environmental contamination can adversely affect the pressure controls that are designed to safely monitor the removal of combustion by-products from the building living spaces.
While it is thus important to shield the open end of a furnace flue pipe, in doing so it is equally important not to overly restrict the flow of flue gas in the pipe. An overly restricted flow passage can, at the best, cause nuisance lockouts of the furnace controls because of the high head pressure or can, at the worst, create unintended flow paths of the flue gases within or around the furnace. Accordingly, a building owner cannot afford to simply rely on a contractor's judgment which might haphazardly or arbitrarily construct such a shielding device.
While various proposed attempts have been found operable with varying success and reliability, there remains a need for improvements in the manner in which such pipes are shielded. It is to these improvements and others as exemplified by the description that embodiments of the present invention are directed.